Method for producing polymer alloy polymer alloy formed article transparent formed article and optical film

ABSTRACT

This invention provides a method for producing a polymer alloy, a polymer alloy as well as a molded article, a transparent molded article and an optical film, which is obtainable by using the polymer alloy. 
     The invention is a method for producing a polymer alloy, which comprises at least: a step  1  of mixing two or more resins incompatible with each other at ambient temperature and pressure with a solvent being in a liquid or gas state at ambient temperature and pressure; a step  2  of heating and applying pressure to said solvent into a high-temperature and high-pressure fluid or a supercritical fluid and mixing the solvent in this state; and, a step  3  of cooling the mixture obtained in said step  2  rapidly to the glass transition temperature or less without releasing the pressure of the mixture.

TECHNICAL FIELD

The present invention relates to a method for producing a polymer alloy,a polymer alloy as well as a molded article, a transparent moldedarticle and an optical film which is obtainable by using the polymeralloy.

BACKGROUND ART

Public attention is focused on polymer alloys having the characteristicswhich are not obtained by a single polymer but obtained by blending twoor more polymers which are incompatible with each other in a usualstate. Especially, in the case where two or more polymers form aultra-micro-phase separation structure, a polymer alloy on which thecharacteristics of each resin are reflected can be obtained. Forexample, an amorphous polymer having high heat resistance is added to anamorphous polymer which has good moldability but low heat resistance toform a polymer alloy, whereby a polymer alloy having good moldabilityand high heat resistance can be manufactured. In addition, unlikecopolymers such as block copolymers or random copolymers, troublesomecopolymerizing operations are not required in the production of thepolymer alloy.

Conventionally, a kneading method is used as a method for producing apolymer alloy having a ultra-micro-phase separation structure byblending two or more polymers which are incompatible with each other ina usual state. In order to obtain a satisfactory ultra-micro-phaseseparation structure, it has been regarded as essential to use somecompatibilizing agent. As the compatibilizing agent, one correspondingto a raw polymer must be selected. However, this selection is not easy,it is difficult to obtain a polymer alloy forming a ultra-micro-phaseseparation structure and having desired characteristics and, also, thereare combinations of polymers for which good compatibilizing agent hasnot been found so far.

Meanwhile, in Japanese Kokai Publication Hei-2-134214, a method isdisclosed in which two types of polymers are melted using supercriticalgas which is present in a gas state at ambient temperature and pressureor a mixture of supercritical gas, these components are thoroughly mixedfor a plenty of time until the viscosity of the polymer mixture isdecreased by at least 10%, then the melt mixture is cooled sufficiently,taking much time to continue mixing until the viscosity of the meltmixture of the polymers reaches again at least the original value andthen the pressure in the mixing container is rapidly released to producea polymer alloy micro-dispersion phase separation structure. Also, inJapanese Kokai Publication Hei-10-330493, a method is disclosed in whicha solvent which is a liquid state at ambient temperature and pressure ischanged to a high temperature and high pressure fluid to makeincompatible two or more polymers compatible with each other and thenthe pressure in the system is rapidly dropped to vaporize the solvent,thereby producing a polymer alloy having a ultra-micro-phase separationstructure 100 nm or less in size.

However, these methods of producing a polymer alloy involve a coolingprocess using the so-called adiabatic expansion in which process thepressure of supercritical gas or a mixture containing supercritical gasis suddenly released or is dropped suddenly from the pressure conditionto thereby vaporize the high pressure and high temperature fluid duringthe course of the process; therefore, a large number of air bubbles aregenerated in the resulting polymer alloy. A troublesome defoamingprocess is required to obtain a transparent molded article by using sucha polymer alloy having air bubbles and, also, there is the case wherethe ultra-micro-phase separation structure of the polymer alloy isbroken by the defoaming process, which considerably limits the range ofthe applications of these methods. There is also the problem that it ishard to scale up the process of vaporizing a solvent suddenly;therefore, the industrialization of the process is difficult.

A method for producing a polymer alloy is disclosed in Japanese KokaiPublication Hei-6-234861, the method using at least one block copolymeror graft copolymer in a supercritical fluid. However, in this method, apressured polymer alloy is expanded by passing it through a fine nozzle;therefore, foaming is easily caused, giving rise to the problem that aprocess of removing air bubbles is inevitable. Also in this method,after glass beads to which a raw resin is stuck are packed in a column,the supercritical fluid is flown through the column to mix the resinwith dissolving the resin; therefore, the ratio of a composition isdetermined by the solubility ratio of each resin. Further, because theamount of a resin which can be treated is small and a raw resin cannotbe supplied continuously, resulting in small throughput.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method forproducing a polymer alloy, a polymer alloy as well as a molded article,a transparent molded article and an optical film which is obtainable byusing the polymer alloy.

A first aspect of the present invention is directed to a method forproducing a polymer alloy, which comprises at least: a step 1 of mixingtwo or more resins incompatible with each other at ambient temperatureand pressure with a solvent being in a liquid or gas state at ambienttemperature and pressure; a step 2 of heating and applying pressure tosaid solvent into a high-temperature and high-pressure fluid or asupercritical fluid and mixing the solvent in this state; and, a step 3of cooling the mixture obtained in said step 2 rapidly to the glasstransition temperature or less without releasing the pressure of themixture. The volume of the solvent in the mixture of the two or moreresins incompatible with each other at ambient temperature and pressureand the solvent being in a liquid state at ambient temperature andpressure is preferably equal to or more than the total volume of saidtwo or more resins incompatible with each other at ambient temperatureand pressure. The two or more resins incompatible with each other atambient temperature and pressure are preferably a thermoplasticnorbornene resin and one or more resins incompatible with thethermoplastic norbornene resin.

A second aspect of the present invention is directed to a polymer alloybeing obtainable by mixing two or more resins incompatible with eachother at ambient temperature and pressure in a high-temperature andhigh-pressure fluid or a supercritical fluid, wherein, at least, when aphase transition phenomenon is observed by using a differentialcalorimeter, the phase transition phenomenon of any resin among said twoor more resins disappears or a phase transition phenomenon is observedat a temperature differing from the temperatures occurring the phasetransition phenomenon of each resin. With regard to the polymer alloyaccording to the second aspect of the present invention, when thehighest and lowest temperatures among the glass transition temperaturesof two or more resins incompatible with each other at ambienttemperature and pressure are Tg_(H) and Tg_(L), respectively, and anabsolute difference between Tg_(H) and Tg_(L) is α, a glass transitiontemperature Tg of the polymer alloy is preferably in the range ofTg′±0.1α for Tg′ calculated by the following equation (1):Σ(w _(i) /Tg _(i))=1/Tg′  (1)in the formula, w_(i) represents the weight percentage of a resin i andTg_(i) represents the glass transition temperature of a resin i.

With regard to the polymer alloy according to the second aspect of thepresent invention, when the highest and lowest temperatures among theglass transition temperatures of two or more resins incompatible witheach other at ambient temperature and pressure are Tg_(H) and Tg_(L),respectively, and an absolute difference between Tg_(H) and Tg_(L) is α,a variation in the glass transition temperature of the polymer alloy ispreferably within 0.3α in the case of processing the polymer alloy in aheat cycle including the requirement for the condition heated to atleast its glass transition temperature or more.

With regard to the polymer alloy according to the second aspect of thepresent invention, said polymer alloy preferably comprises a transparentresin and at least one or more resins incompatible with the transparentresin and, said transparent resin and the resins incompatible with thetransparent resin preferably form a ultra-micro-phase separationstructure 100 nm or less in size.

A molded article which is obtainable by molding the polymer alloyaccording to the second aspect of the present invention and atransparent molded article which is obtainable by melt-molding thepolymer alloy according to the second aspect of the present inventionare also respectively one of the present invention. With regard to amethod for producing the molded article or transparent molded article,the polymer alloy is preferably molded at a temperature higher than thephase transition initiation temperature of the ultra-micro-phaseseparation structure of the polymer alloy found by a differencecalorimeter.

An optical film which is obtainable by using the polymer alloy accordingto the present invention is also one of the present invention.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is a schematic view showing one example of a production apparatusfor producing a polymer alloy according to the present invention, and

FIG. 2 is a schematic view showing one example of a production apparatusfor producing a polymer alloy according to the present invention.

In these figures, 1 represents a production container, 2 represents aheater, 3 represents a metal salt, 4 represents a thermocouple, 5represents a metal salt molten bath, 6 represents an extruder, 7represents a syringe feeder, 8 represents a sheath heater, 9 representsa quantitative pump, 10 represents a metal salt molten bath, 11represents an electric furnace, 12 represents a cooing machine, 13represents a back pressure regulating valve and 14 represents a recoverytank.

DETAILED DISCLOSURE OF THE INVENTION

The present invention will be hereinafter described in detail.

A method for producing a polymer alloy according to a first aspect ofthe present invention comprises at least a step 1 of mixing two or moreresins incompatible with each other at ambient temperature and pressurewith a solvent being in a liquid or gas state at ambient temperature andpressure; a step 2 of heating and applying pressure to said solvent intoa high-temperature and high-pressure fluid or a supercritical fluid andmixing the solvent in this state; and, a step 3 of cooling the mixtureobtained in said step 2 rapidly to the glass transition temperature orless without releasing the pressure of the mixture. In thisspecification, the polymer alloy means a mixture of resins having aphase separation structure in which each resin is uniformly dispersed asa small resin domain in a mixed state and, preferably, means a mixtureof resins having a ultra-micro-phase separation structure in which eachresin domain has a size of 100 nm or less. Also in this specification,the polymer alloy may have the state that the above-mentioned resindomains are very small to the extent that resins are mutually dissolvedcompletely.

In the method for producing a polymer alloy in the first aspect of thepresent invention, at first, two or more resins incompatible with eachother at ambient temperature and pressure are mixed with a solvent whichis a liquid state or in a gas state at ambient temperature and pressurein the step 1.

Examples of the solvent which is a liquid state at ambient temperatureand pressure include water, organic solvents and the like. Examples ofthe organic solvent include hydrocarbon type organic solvents such ashexane, heptane, cyclohexane and toluene; ether type organic solventssuch as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane; estertype organic solvents such as ethyl acetate and butyl acetate; ketonetype organic solvents such as acetone, methyl ethyl ketone and methylisobutyl ketone; alcohol type organic solvents such as methanol, ethanoland isopropyl alcohol; and dimethylsulfoxide and N,N-dimethylformamide.

Examples of the solvent which is in a gas state at ambient temperatureand pressure include N₂; CO₂; N₂O; chlorofluorocarbon such aschlorodifluoromethane and dichlorotrifluoroethane or hydrofluorocarbon;low-molecular alkanes such as n-butane, propane and ethane;low-molecular alkenes such as ethylene; and ammonia.

In particular, solvents which are liquid at an ambient temperature (25°C.) at ambient pressure (0.1 MPa) and have critical temperature andcritical pressure are preferable. If the solvent is in a gas state atambient temperature and pressure, pressure must be gradually releasedunder control to prevent the solvent from being foamed. On the otherhand, if the solvent is in a liquid state at ambient temperature andpressure, the internal pressure in a mixing container is not changedwhen pressure is released and there is therefore no possibility offoaming. These solvents may be used either singly or in combinations oftwo or more.

Particularly in the case of containing a thermoplastic norbornene resinas one of the two or more resins incompatible with each other, water ispreferably used as the solvent. Even a thermoplastic norbornene resinwhich is only soluble in cyclohexane at ambient temperature and pressurein practical use can be dissolved sufficiently in water made to be ahigh-temperature and high-pressure fluid or a supercritical fluidreduced in polarity. Because the thermoplastic norbornene resin isinsoluble in water at ambient temperature and pressure, it is taken outwith ease and is therefore easily handled. It is also preferable to usean alcohol as the solvent. Because alcohols are also put in ahigh-temperature and high-pressure state or supercritical state atrelatively low temperatures, the resins are not thermally decomposed andare therefore preferably used.

The above-mentioned solvent preferably occupies a volume to the extentthat the resins can be stirred. Specifically, the volume of the solventput in a liquid state at ambient temperature and pressure is preferablyequal to or more than the total volume of the above-mentioned two ormore resins incompatible with each other at ambient temperature andpressure.

The viscosity of the solvent put in a high-temperature and high-pressurestate or in a supercritical state is high and can be made to be higherthan that of the resin. Therefore, even a resin which has a highviscosity and is mixed with difficulty can be mixed with other resins bystirring using the solvent made to have a high viscosity in ahigh-temperature and high-pressure state or in a supercritical state.

It is to be noted that a compatibilizing agent may be added to theabove-mentioned solvent according to the need. Examples of thecompatibilizing agent include oligomers or polymers in which segmentsrespectively soluble in each component are present. When thecompatibilizing agent is a polymer, it may be any of a random polymer,block polymer and graft polymer.

Also, a polymer can be made to have a function as the compatibilizingagent by modifying a part of the structure of the polymer according tothe need. Examples of the compatibilizing agent include maleic acidmodified poly(propylene), carboxylic acid modified poly(propylene),amino group-terminal nitrile-butadiene rubber, carboxylic acid modifiedpoly(ethylene), chlorinated poly(ethylene), sulfonated poly(styrene),hydroxyl group-terminal polyolefin, hydroxyl group-terminalpoly(butadiene), maleic acid modified ethylene-butylene rubber andpoly(ethylene-co-acrylic acid). Also, examples of polymers effective asa compatibilizing agent for graft type polymers include polyolefins witha vinyl polymer grafted to the side chain, poly(carbonate) with a vinylpolymer grafted to the side chain, and the like. Examples ofcommercially available compatibility promoter include “Modiper”(manufactured by NOF Corporation), “Admer” (manufactured by MitsuiChemicals Inc.) and the like.

In the method for producing a polymer alloy according to the firstaspect of the present invention, next, a step 2 of heating andpressurizing the above-mentioned solvent to make the solvent into ahigh-temperature and high-pressure fluid or a supercritical fluid andmixing the solvent in this state is carried out.

The temperature of the high-temperature and high-pressure fluid orsupercritical fluid is preferably 100 to 700° C. When the temperature isless than 100° C., there is the case where the ultra-micro-phaseseparation structure of the resulting polymer alloy is insufficientlyformed. When the temperature is more than 700° C., there is the casewhere the resin is decomposed, the energy required for raisingtemperature is very large and large energy loss is caused, increasingthe cost which is uneconomical. The temperature is more preferably 100to 400° C.

The pressure of the above-mentioned high-temperature and high-pressurefluid or supercritical fluid is preferably 0.5 to 100 MPa. When thepressure is less than 0.5 MPa, the ultra-micro-phase separationstructure of the resulting polymer alloy is insufficiently formed. Whenthe pressure is more than 100 MPa, there is the case where the energyrequired for raising pressure is very large, increasing the cost whichis uneconomical. The pressure is more preferably 0.5 to 60 MPa.

The process time required for mixing the resins in a high-temperatureand high-pressure state or in a supercritical state is preferablyshorter. If the mixing time is short, the decomposition of the resin canbe suppressed. When the mixing time is long, there is the case where theresulting resin is decomposed into a liquid. The mixing time is, thoughit differs depending on process temperature, within preferably 30minutes, more preferably 20 minutes, still more preferably 10 minutes at400° C. or more and within preferably one hour, more preferably 30minutes at 400° C. or less.

Examples of a method enabling the mixing to be completed in a short timelike this include a method in which each resin is melted and mixed inadvance. Namely, if each resin is melted and mixed in advance, it israpidly made into a polymer alloy by putting each resin in ahigh-temperature and high-pressure state or in a supercritical state.This makes it possible to be free from a possibility that a polymeralloy having a composition different from a raw material composition isobtained but makes it possible to obtain a polymer alloy having almostthe same composition as the raw material composition.

Also, the time required to reach a high-temperature and high-pressurestate or a supercritical state is preferably short. If the time isshort, the decomposition of the resin can be suppressed. Examples of amethod for putting each resin in a high-temperature and high-pressurestate or supercritical state in short time include a method in which themixed resins are preheated in advance under an ambient pressureenvironment.

In the method for producing a polymer alloy according to the firstaspect of the present invention, a step 3 of cooling the mixtureobtained in the step 2 to the glass transition temperature or lessrapidly without releasing the pressure of the mixture is carried out.

In the conventional technique, a method for cooling by heat absorptiondue to adiabatic expansion is adopted. However, in this method, it ishard to control pressure and cooling speed varies according to adifference in pressure release condition, arousing a possibility thatmacro-phase separation is caused. Also, a polymer alloy containing alarge number of air bubbles is only obtained. The present inventors havemade earnest studies and, as a result, found that if the systemtemperature is cooled rapidly to the glass transition temperature orless, an optional micro-phase separation structure can be madecorresponding to the cooling speed and a polymer alloy containing no aircell is obtained. Although there is no limitation to the cooling speedin relation to the above-mentioned term “cooled rapidly”, the rate of adrop in temperature from the production temperature to the glasstransition temperature is preferably 25° C./min or more. When thetemperature drop rate is less than 25° C./min, there is the case wherethe resin is deteriorated. The temperature drop rate is more preferably50° C./min or more. When there are plural glass transition temperatures,the temperature may be cooled rapidly to the glass transitiontemperature of a resin exhibiting the lowest glass transitiontemperature or may be cooled rapidly to the glass transition temperatureof each resin step by step repeatedly. In this case, an optional phasestructure can be formed by changing the cooling rate. For example, inthe case where the upper limit critical consolute temperature is higherthan the glass transition temperature of a matrix component and theglass transition temperature of the domain component is higher than theglass transition temperature of a matrix component, a polymer alloyhaving not a perfectly compatible structure but a micro-phase separationstructure can be obtained if the resin mixture is maintained at atemperature higher than the glass transition temperature of the matrixcomponent to precipitate the domain component and then cooled quickly.

In the case where the glass transition temperature of the resin isambient temperature or less, the phase structure can be maintained tosome extent if the resin mixture is cooled quickly to at least ambienttemperature. The method for producing a polymer alloy comprising atleast a step 1 of mixing two or more resins incompatible with each otherat ambient temperature and pressure with a solvent being in a liquid orgas state at ambient temperature and pressure, a step 2 of heating andapplying pressure to the solvent into a high-temperature andhigh-pressure fluid or a supercritical fluid and mixing the solvent inthis state, and a step 3 of cooling the mixture obtained in the step 2rapidly to room temperature or less without releasing the pressure ofthe mixture in this manner is also one of the present invention.

In the method for producing a polymer alloy according to the firstaspect of the present invention, the size of the phase separated domainparticle of the polymer alloy can be controlled by optionally settingthe temperature and pressure in a production container before the startof mixing or in the initial stage of mixing. Also, the polymer alloy canbe obtained as a foaming body by regulating the temperature and pressurewhen the produced polymer alloy is taken out and by choosing a solvent.

In the method for producing a polymer alloy according to the firstaspect of the present invention, the solvent is not decomposed even ifit is in a liquid state at ambient temperature and pressure, and theproduced polymer alloy can be taken out as particles. After theparticles are taken out, they are filtered and dried, whereby a polymeralloy can be easily recovered. Also, the collected resin may be moldedinto an optional shape by various molding methods.

No particular limitation is imposed on the resin to which the method forproducing a polymer alloy according to the first aspect of the presentinvention is preferably applicable. Examples of the applicable resininclude a poly(ethylene), poly(propylene), poly(ethylene-co-vinylacetate), poly(acrylonitrile-co-stylene), ABS resins, that isacrylonitrile-butadiene-styrene, poly(vinyl chloride), acryl resins,methacryl resins, poly(styrene), poly(tetrafluoroethylene),poly(chlorotrifluoroethylene), poly(vinylidene fluoride),poly(ethylene-co-vinyl alcohol), vinylidene chloride resins, chlorinatedpoly(ethylene), poly(dicyclopentadiene), methylpentene resins,poly(butylene), poly(phenylene ether)s, poly(amide)s, poly(phenylenesulfide)s, poly(ether ether ketone)s, poly(allyl ether ketone)s,poly(amide imide)s, poly(imide)s, poly(ether imide)s, poly(sulfone)s,poly(ether sulfone), norbornene resins, poly(vinyl alcohol), urethaneresins, poly(vinyl pyrrolidone), poly(ethoxy ethyl methacrylate),poly(formaldehyde), cellulose diacetate, poly(vinyl butyral), and like.Particularly, it has been hard to prepare a polymer alloy by using acombination of resins largely differing in polarity. On the contrary,the method for producing a polymer alloy according to the first aspectof the present invention makes it possible to obtain a polymer alloywith ease by using such a combination. Examples of the above-mentionedcombination of resins differing in polarity include the cases where theresin having low polarity is a polyolefin resin and the polar resin isan acryl resin, styrene resin, fluorine resin, poly(ether etherketone)s, poly(carbonate) or the like.

Unlike conventional methods, the method for producing a polymer alloyaccording to the first aspect of the present invention does not involvethe step of vaporizing a liquid solvent quickly at ambient temperatureand pressure. Therefore, it is unnecessary to control pressure, showingthat this method has high productivity, limits the generation of airbubbles, improving the quality and enables scale-up with ease.

In the method for producing a polymer alloy according to the firstaspect of the present invention, a polymer alloy whose phase structureis scarcely broken even by heating can be obtained. Therefore, it ispossible to develop the qualities of other resins without damaging theexcellent qualities of each resin. Also, because the phase structure ofa polymer alloy can be maintained during melt-molding, an excellentmolded article can be obtained.

FIG. 1 shows one example of a production apparatus used in the methodfor producing a polymer alloy according to the first aspect of thepresent invention. In the production apparatus shown in FIG. 1, aproduction container 1 is sunk in a metal salt 3. The metal salt 3 ismelted under heating by a heater 2 and its temperature is controlled bya thermocouple 4.

It is to be noted that in the production apparatus shown in FIG. 1, ametal salt molten bath is used as heating means. Besides the moltenbath, heating means such as an electric heater, a burner, combustiongas, steam, heating medium and sand bath may be used.

The production container 1 is also used for production in severeconditions extending to supercritical range or the vicinity ofsupercritical range and one made of a material and having a thicknesscapable of standing against these conditions is therefore used as theproduction container 1. Examples of a material of the productioncontainer 1 include carbon steel, special steel such as Ni, Cr, V or Mosteel, austenite type stainless steel, hastelloy and titanium, or thoseobtained by lining these materials with glass, ceramic, carbide or thelike or those obtained by cladding these materials with other metals.

Also, no particular limitation is imposed on the shape of the productioncontainer 1 and, for example, a vessel type, tube type or containershaving a specific shape may be used. In particular, a vessel type ortube type is preferable in consideration of heat resistance and pressureresistance. In the case of a batch system, an autoclave and a tubularreactive tube is preferable.

It is preferable to place a hard ball or obstacle having a predeterminedshape which is made of a metal, ceramic or the like in the productioncontainer 1 to cause a turbulent flow. If the hard ball is provided inthe production container 1, a turbulent flow occurs by means of shaking,which improves stirring efficiency, whereby reaction efficiency can beheightened. Further, if the production container 1 is packed with hardballs, this is preferable because stirring efficiency is heightened onlyby shaking the container.

The packing ratio of the hard ball is preferably 20 to 80%. When thepacking ratio is out of this range, stirring efficiency is lowered. Inthis case, it is preferable to use two or more types of hard ballshaving different diameters. This can improve the packing ratio and thestirring efficiency.

It is also preferable to provide the production container 1 with a platethrough which orifices are opened. If the production container 1 isprovided with the plate through which orifices are opened, stirringefficiency is improved and hence reaction efficiency is improved since aturbulent flow is caused by means of shaking.

As examples of the method for producing a polymer alloy according to thepresent invention by using the production apparatus shown in FIG. 1, thefollowing method is given. Specifically, two or more resins incompatiblewith each other and a solvent are poured into a production apparatus 1,which is then perfectly sealed and then poured into the above-mentionedmetal salt molten bath 5 to heat and pressurize the above-mentionedsolvent into a high-temperature and high-pressure fluid or supercriticalfluid.

The system is maintained in this condition for a predetermined time tomake these two or more resins compatible. Then, the production container1 is poured into a cooling bath quickly to cool it rapidly. After thecontainer 1 is cooled sufficiently, a polymer alloy produced in theproduction container 1 is taken out.

FIG. 2 shows another example of a production apparatus used in themethod for producing a polymer alloy according to the first aspect ofthe present invention. In the production apparatus shown in FIG. 2, rawresins are supplied from an extruder 6 and a syringe feeder 7,respectively. The supplied resins are heated and melted by a sheathheater 8. On the other hand, a fluid which can be made into ahigh-temperature and high-pressure fluid or a supercritical fluid is fedby a quantitative pump 9 to a metal salt molten bath 10, where it isheated. The heated fluid becomes a high-temperature and high-pressurefluid or a supercritical fluid. The mixed resins in a molten state aremixed with the high-temperature fluid and is then kept at a fixedtemperature in an electric furnace 11. Then, the mixed resins arechanged to a polymer alloy before they reach a cooler 12. The fluidcooled in the cooler 12 is neither a high-temperature and high-pressurefluid nor a supercritical fluid. The resulting polymer alloy is reservedtogether with the fluid in a recovery tank 14 provided with a backpressure regulating valve 13.

A second aspect of the present invention is directed to a polymer alloybeing obtainable by mixing two or more resins incompatible with eachother at ambient temperature and pressure in a high-temperature andhigh-pressure fluid or a supercritical fluid, wherein, at least, when aphase transition phenomenon is observed by using a differentialcalorimeter, the phase transition phenomenon of any resin among said twoor more resins disappears or the phase transition phenomenon is observedat a temperature differing from the temperatures occurring the phasetransition phenomenon of each resin.

The polymer alloy of the second aspect of the present invention isobtainable by mixing two or more resins incompatible with each other atambient temperature and pressure in a high-temperature and high-pressurefluid or a supercritical fluid.

Even in the case of two or more resins incompatible with each other atambient temperature and pressure conditions, a polymer alloy can beobtained by mixing these resins in a high-temperature and high-pressurefluid or a supercritical fluid.

The polymer alloy of the present invention has the characteristics thatwhen a phase transition phenomenon is measured using a differentialcalorimeter, at least the phase transition phenomenon of any resin amongthe above-mentioned two or more resins disappears or a phase transitionphenomenon is observed at a temperature differing from the temperaturesoccurring the phase transition phenomenon of each resin. This shows thatthe polymer alloy has a ultra-micro-phase separation structure.

Usually, whether a polymer alloy has a ultra-micro-phase separationstructure or not is confirmed by dying it by using ruthenium tetraoxideor the like to observe it by using an electron microscope. If thepolymer alloy has a ultra-micro-phase separation structure, it can beobserved that the polymer alloy is put in a mixed state in which eachresin is dispersed uniformly as a small resin domain. However, there isthe case where two or more resins are observed in the state that theyare completely dissolved mutually and each resin domain is not observedby an electron microscope depending on the type of resin. In this case,whether or not the polymer alloy has a ultra-micro-phase separationstructure can be confirmed by measuring the phase transition temperatureof each resin in advance by using a differential calorimeter and then bymeasuring the phase transition temperature of the polymer alloy obtainedusing these resins. Specifically, in the case where these resins arecompletely dissolved mutually or are in a dispersed state in which eachresin is in a uniformly dispersed and mixed state as a very small resindomain, the phase transition temperature is a single one. It may betherefore inferred that a polymer alloy is formed if the phasetransition phenomenon of any one of the resins which phenomenon has beenobserved until that time disappears and is hence not observed when thepolymer alloy reaches the phase transition temperature of that resin ornew phase transition temperature at which a phase transition phenomenonnewly occurs is observed at temperatures differing from the phasetransition temperature of each resin which is observed before.

Also, the size of the above-mentioned resin domain may be calculated bythe Zimm's equation given by the following formula after a polymer alloyis molded into a film which is then subjected to measurement using laserlight scattering to measure the scattering vector dependency of thescattering strength.1/I(s)≈1/<Mw>·[1+(s ²/3)·<Rg>_(z)]Incidentally, s=4πsinθ/λ.In the formula, 2θ represents a scattering angle, λ represents thewavelength of a power source, <Rg>_(z) represents the size of a domainobserved and I(s) represents a scattering strength for a scatteringvector s.

Also, the size of the above-mentioned resin domain may be found in thefollowing manner. Specifically, a polymer alloy is subjected to smallangle X-ray scattering measurement to measure the angle dependency ofdiffraction strength to calculate the size by the Guinier's equationgiven by the following formula.1n(I(s))≈1n(I(0))−s ² ·Rg ²/3In the formula, Rg represents a domain size and I(0) represents ascattering strength at a scattering angle of 0.

With regard to the polymer alloy of the present invention, when highestand lowest temperatures among the glass transition temperatures of twoor more resins incompatible with each other at ambient temperature andpressure are Tg_(H) and Tg_(L), respectively, and an absolute differencebetween Tg_(H) and Tg_(L) is α, the glass transition temperature Tg ispreferably in the range of Tg′±0.1α for Tg′ calculated by the followingequation (1).Σ(w _(i) /Tg _(i))=1/Tg′  (1)In the formula, w_(i) represents the weight percentage of a resin i andTg_(i) represents the glass transition temperature of a resin i. It ispreferable.

The above-mentioned formula (1) is called Fox's equation and Tg′calculated by this equation is theoretical glass transition temperaturewhen a polymer alloy has a complete compatible body structure. If theglass transition temperature Tg of a polymer alloy falls in the range ofTg′±0.1α when the polymer alloy is observed using a differentialcalorimeter, the polymer alloy is considered to have a ultra-micro-phaseseparation structure.

The polymer alloy according to the present invention preferably has thecharacteristics that a variation in the glass transition temperature ofthe polymer alloy when the polymer alloy is processed in a heat cycleincluding the requirement for the condition that it is heated to atleast its glass transition temperature or more is preferably within0.3α. Usually, when two or more resins incompatible with each other aremixed with each other by using mechanical shearing force such askneading and then cooled quickly or when each resin is dissolved in aproper solvent without pressurizing it and then cooled quickly, thedomain structure is very unstable to heat even if the domain structureis fixed, with the result that the glass transition temperature ischanged by applying a heat cycle at the glass transition temperature ormore (Polym. Eng. Sci. vol 27, 1953 (1987)). Therefore, if the polymeralloy has such characteristics, the physical properties of the polymeralloy are changed when the polymer alloy is molded so that the originalcharacteristics of the polymer alloy are lost. The variation is morepreferably within 0.25α.

No particular limitation is imposed on the resins used in the polymeralloy in the present invention insofar as they are incompatible witheach other or have poor compatibility with each other. Examples ofcombinations of these resins include resin mixtures of crystal resinsand amorphous resins; ionic resin mixtures of cationic or anionic resinshaving poor compatibility with each other; resin mixtures of non-polarresins and polar resins; mixtures of resins differing largely in glasstransition temperature or melting point from each other and mixtures ofresins largely differing in viscosity from each other. Also, eachstructure of the above-mentioned resins may be either a linear orbranched structure or the resin may have a crosslinking structure.Moreover, the regularity of these resins may be isotactic, syndiotacticor atactic. Also, the above-mentioned resins may be copolymers such asblock copolymers, random copolymers and graft copolymers. Also, theresins may be oligomers or high-molecular or ultra-high molecularpolymers.

In the case of aiming at optical applications, the above-mentionedresins preferably have high transparency. There is no particularlimitation to the highly transparent resin. Examples of the resininclude thermoplastic norbornene resins, methyl poly(methacrylate),poly(styrene), poly(carbonate), polyesters and the like. Also, when theresins have refractive indexes close to each other, this is preferablebecause it is easy to obtain transparency. Also, there are applicationsneeding a low refractive index and resins having a low refractive indexsuch as thermoplastic norbornene resins, methyl poly(methacrylate) andpoly(styrene) are preferable in such optical applications.

The polymer alloy obtained with an aim at optical applications issuperior in transparency, heat resistance, hygroscopicity, lowbirefringent properties and moldability. Therefore, the polymer alloy ofthe present invention, making use its characteristics, can be widelyused in various applications including optical applications such aslenses, e.g., lenses for general cameras, lenses for video cameras,telescope lenses, spectacle lenses and lenses for laser beams, opticaldisks, e.g., optical videodisks, audiodisks, document file disks andmemory disks, optical materials, e.g., optical fibers, image receivingtransfer sheets and various films and sheets and packages for variouselectronic devices, window glasses, print boards, sealing materials andbinders for inorganic or organic compounds.

When the polymer alloy of the present invention contains a thermoplasticnorbornene resin, the moldability, moisture permeability, adhesivenessand the like are improved without impairing the heat resistance andtransparency of the thermoplastic norbornene resin. Also, thermaldeterioration and the occurrence of defects during melt-molding can besuppressed.

No particular limitation is imposed on the thermoplastic norborneneresin. Examples of the thermoplastic norbornene resin may includehydrogenated products of ring-opened polymers (including copolymers) ofnorbornene monomers; and copolymers of norbornene monomers and olefinicmonomers such as ethylene and/or α-olefin. These resins havesubstantially no unsaturated bond.

As the norbornene monomer which is to be a raw material for thethermoplastic norbornene resin, those described in Japanese KokaiPublication Hei-5-39403, Japanese Kokai Publication Hei-5-212828 andJapanese Patent No. 3038825, 3019741 and 3030953 may be used. Examplesof these monomers may include norbornene, methanooctahydronaphthalene,dimethanooctahydronaphthalene, dimethanododecahydroanthracene,dimethanodecahydroanthracene and trimethanododecahydroanthracene ortheir substitution products; dicyclopentadiene,2,3-dihydrocyclopentadiene, methanooctahydrobenzoindene,dimethanooctahydrobenzoindene, methanodecahydrobenzoindene,dimethanodecahydrobenzoindene, methanooctahydrofluorene anddimethanooctahydrofluorene or their substitution products. Thesenorbornene monomers may be used either singly or in combinations of twoor more.

No particular limitation is imposed on the substituent in theabove-mentioned substitution products and conventionally knownhydrocarbon groups or polar groups may be used as the substituent.Examples of the substituent include an alkyl group, alkylidene group,aryl group, cyano group, halogen atom, alkoxycarbonyl group, pyridylgroup and the like. Examples of the substitution product include5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene,5-butyl-2-norbornene, 5-ethylidene-2-norbornene,5-methoxycarbonyl-2-norbornene, 5-cyano-2-norbornene,5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norbornene,5-phenyl-5-methyl-2-norbornene and the like.

The number average molecular weight of the above-mentioned thermoplasticnorbornene resin is usually preferably 5000 to 200000 though noparticular limitation is imposed on it. When the number averagemolecular weight is less than 5000, there is the case where themechanical strength of a molded product (especially, optical films)produced from the polymer alloy of the present invention is insufficientwhereas when the number average molecular weight is more than 200000,there is the case where the moldability is impaired. The number averagemolecular weight is more preferably 7000 to 35000, still more preferably8000 to 30000. The number average molecular weight of theabove-mentioned thermoplastic norbornene resin may be measured by gelpermeation chromatography (GPC).

The thermoplastic norbornene resin used in the present invention may beeither a resin having a polar group or a resin having no polar group. Inthe case of the thermoplastic norbornene resin having a polar group, thepolar group may exist to the extent that the optical characteristics andmoldability are not impaired and the presence of the polar group israther preferable to impart proper moisture permeability to a moldedarticle.

There is no particular limitation to the polar group like this. Examplesof the polar group include a halogen group (chlorine group, brominegroup and fluorine group), hydroxyl group, carboxylic acid group, estergroup, amino group, acid anhydride group, cyano group, silyl group,epoxy group, acryl group, methacryl group, silanol group and the like.In particular, an ester group and acid anhydride group which can providereactivity by deprotection are preferable.

Examples of the thermoplastic norbornene resin available as commercialproducts among the above-mentioned thermoplastic norbornene resinsinclude “Arton” (manufactured by JSR Corporation) as resins having apolar group and “Zeonor” (manufactured by Zeon Corporation) as resinshaving no polar group.

In the case of using the above-mentioned thermoplastic norbornene resinin the polymer alloy of the present invention, no particular limitationis imposed on the incompatible resin used in combination with thethermoplastic norbornene resin to form the polymer alloy. Examples ofthe incompatible resin include poly(ethylene), poly(propylene),poly(ethylene-co-α-olefin)s; poly(ethylene-co-vinyl acetate);poly(ethylene-co-(meth)acrylate) or poly(ethylene-co-(meth)acrylic acid)such as poly(ethylene-co-ethylacrylate); polyolefin resins such aspoly(butadiene); poly((meth)acrylate ester) such as methylpoly(methacrylate) and butyl poly(acrylate); poly(carbonate); poly(vinylacetate); poly(amide)s; poly(acetal)s; poly(phenylene ether)s; ionomers;poly(vinyl chloride); poly(imide)s; poly(ester)s; poly(ethylene oxide);poly(arylate); ABS resins; plastic fluorides; poly(vinylidene fluoride);poly(vinylidene chloride); poly(styrene); poly(sulfone)s; poly(vinylether)s; poly(vinyl alcohol); and poly(lactate). In particular,non-crystalline resins or less-crystalline resins such as methylpoly(methacrylate), poly(carbonate), poly(sulfone)s, triacetylcelluloses- and poly(vinyl alcohol) or resins having a small crystalsize though they are crystalline resins are preferably used for anoptical film which needs transparency.

When at least one of the above-mentioned two or more resins used in thepolymer alloy of the present invention is a transparent resin, theabove-mentioned transparent resin and the resin incompatible with thetransparent resin preferably form a ultra-micro-separation structure 100nm or less in size. When the phase separation structure is more than 100nm, transparency, haze and the like are reduced and there is thereforethe possibility of the obtained polymer alloy being unfit for opticaluses. It is also possible to impart moisture permeability to thethermoplastic norbornene resin by mixing a resin having high moisturepermeability to make a ultra-micro-separation structure 100 nm or lessin size.

As to the compounding ratio of the above-mentioned two or more resinsincompatible with each other at ambient temperature and pressureconditions in the polymer alloy of the present invention, the resinincompatible with the above-mentioned base resin is compounded in anamount of preferably 0.01 to 100 parts by weight based on 100 parts byweight of the base resin. The ratio is more preferably 0.01 to 15 partsby weight, still more preferably 3 to 10 parts by weight.

Also, in the case of using the thermoplastic norbornene resin, when thecompounding amount of the incompatible resin used to form the polymeralloy in combination with the thermoplastic norbornene resin is definedbased on another standard, the amount preferably falls within a rangewhere a reduction in temperature caused by compounding theabove-mentioned thermoplastic norbornene resin can be kept within 30° C.in order to maintain the heat resistance and moldability of theresulting polymer alloy. When the reduction in glass transitiontemperature is more than 30° C., the heat resistance which thethermoplastic norbornene resin originally has is impaired and there istherefore the case where the range of use is largely limited inapplications such as optical films.

Known additives such as an antioxidant, ultraviolet absorber, lubricantand antistatic agent may be compounded in the polymer alloy of thepresent invention to the extent that the object of the present inventionis not impaired.

Examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol,2,2′-dioxy-3,3′-di-t-butyl-5,5′-dimethyldiphenylmethane,tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane,and the like. Examples of the ultraviolet absorber include2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and thelike.

When the polymer alloy of the second aspect of the present inventioncontains the above-mentioned thermoplastic norbornene resin, the polymeralloy is superior in transparency, heat resistance, low hygroscopicity,low birefringent properties and moldability. Therefore, the polymeralloy, making use its characteristics, can be widely used in variousapplications including optical applications such as lenses, e.g., lensesfor general cameras, lenses for video cameras, telescope lenses,spectacle lenses and lenses for laser beams, optical disks, e.g.,optical videodisks, audiodisks, document file disks and memory disks,optical materials, e.g., optical fibers, image receiving transfer sheetsand various films and sheets and packages for various electronicdevices, window glasses, print boards, sealing materials and binders forinorganic or organic compounds.

A molded article and a transparent molded article being obtainable byusing the polymer alloy of the present invention are also respectivelyone of the present invention.

The molded article being obtainable by using the polymer alloy of thepresent invention may be obtainable by using known molding means, forexample, extrusion molding, injection molding, compression molding, blowmolding and calender molding.

Although no particular limitation is imposed on a method for producingthe molded article obtained using the polymer alloy of the presentinvention, it is preferable to mold the polymer alloy at temperatureshigher than the phase transition initiation temperature of the polymeralloy ultra-micro-phase separation structure which temperature is foundby a differential calorimeter. However, the polymer alloy is preferablymolded at temperatures not higher than the phase transition initiationtemperature by 30° C. or more. If the temperature is too high, there isa possibility that the ultra-micro-phase separation structure is brokenduring molding. It is to be noted that the polymer alloy may besubjected to injection molding or extrusion molding directly from thesupercritical state or high-temperature and high-pressure state.

Also, when the polymer alloy is molded into an optical film, it ispreferably heat-pressed at temperatures not higher than the phasetransition initiation temperature by 30° C. or more. It is morepreferably heat-pressed at temperatures not higher by 30° C. or morethan the glass transition temperature of the resin compounded in thehighest compounding ratio. This ensures that even in the case where thepolymer alloy foams or in the case where the polymer alloy does not foambut embraces a few air bubbles, a transparent optical film with no airbubbles present in the inside thereof can be obtained without breakingthe ultra-micro-phase structure. Also, if heating is continued for along time even though the molding temperature is not high, theultra-micro-phase separation structure is gradually lost and it istherefore preferable to make the molding time as short as possible.

In addition, a hardcoat layer containing an inorganic compound, organicsilicon compound such as a silane coupling agent, acryl type resin,vinyl type resin, melanin resin, epoxy resin, fluorine type resin,silicone resin or the like may be formed on the surface of the moldedarticle being obtainable by using the polymer alloy of the presentinvention. This makes it possible to improve the heat resistance,optical characteristics, chemical resistance, abrasive resistance,moisture permeability and the like of the molded article.

Examples of means for forming the hardcoat layer may include knownmethods such as a heat-curing method, ultraviolet ray-curing method,vacuum deposition method, sputtering method and ion plating method.

When the polymer alloy of the present invention contains thethermoplastic norbornene resin as its structural component, it ispreferably applicable to optical films, such as particularly, phasedifference films and polarizing plate protective films by maximallymaking use of the point that it is superior in moldability and heatresistance.

An optical film obtained using the polymer alloy of the presentinvention is also one of the present invention.

The optical film of the present invention preferably has a tearingstrength of 0.1 N or more. If the tearing strength is less than 0.1 N,there is the case where the range of applications as optical films islimited and this tendency is significant in the case of, particularly, athin film having a thickness of 10 μm or less.

The optical film of the present invention preferably has a total lighttransmittance of 60% or more. When the transmittance is less than 60%,there is the case where the range of applications as optical films islimited. The transmittance is preferably 70% or more, more preferably80% or more.

The optical film of the present invention preferably a haze of 20% orless. When the haze is less than 20%, there is the case where the rangeof applications as optical films is limited. The haze is more preferably10% or less, still more preferably 5% or less.

The optical film of the present invention may be obtainable by, forexample, an extrusion molding method, press molding method or the like.The thickness of the optical film of the present invention is usually 10to 300 μm.

The polymer alloy of the present invention ensures that the qualities ofother resins can also be developed without impairing the excellentqualities of each resin. Also, the phase separation structure isscarcely broken even by heating, so that the micro-phase separationstructure of the polymer alloy is maintained during melt-molding. It istherefore possible to obtain an excellent molded article.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail by way ofexamples, which, however, are not intended to be limiting of the presentinvention.

EXAMPLES 1, 2, 4, 5 AND 6

A batch type production container 1 (tube type container, made ofSUS316, Tube Bomb Reactor, internal volume: 100 mL) shown in FIG. 1 wascharged with a solvent, a thermoplastic norbornene resin (Tg=161° C.), amethyl poly(methacrylate) resin (PMMA, Tg=110° C.), a poly(carbonate)(PC, Tg=141° C.) and an poly(ethylene-co-vinyl acetate) (EVA, T_(m)=78°C.) in each predetermined amount according to the formulation shown inTable 1 and the atmosphere in the production container was completelyreplaced with nitrogen.

Next, the production container 1 was sunk in a metal salt molten bath 5(manufactured by Shin-Nippo Chemical Co., Ltd.) equipped with amicro-heater 2 (manufactured by Sukegawa Electric Co., Ltd.) and treatedin the condition of the temperature and pressure shown in Table 1 for apredetermined time. Then, the production container 1 was cooled rapidlyin a cooled bath and then ice-cooled and the obtained polymer alloy wasseparated and dried.

The obtained polymer alloy was heat-pressed at 185° C. to manufacture afilm 40 μm in thickness.

EXAMPLE 3

A batch type production container 1 (tube type container, made ofSUS316, Tube Bomb Reactor, internal volume: 100 mL) shown in FIG. 1 wascharged with a thermoplastic norbornene resin and a PMMA in eachpredetermined amount according to the formulation shown in Table 1.Then, carbon dioxide was liquefied and then added in the productioncontainer until the pressure in the container was 10 MPa and thecontainer was sealed. Thereafter, the production container 1 was sunk ina metal salt molten bath 5 (manufactured by Shin-Nippo Chemical Co.,Ltd.) equipped with a micro-heater 2 (manufactured by Sukegawa ElectricCo., Ltd.) to heat the production container 1 quickly, thereby raisingthe temperature and pressure in the container to 200° C. and 35 MPa,respectively. This condition was kept for 180 minutes. After that, theproduction container 1 was cooled in air and the obtained polymer alloywas then dried.

The obtained polymer alloy was heat-pressed at 185° C. to manufacture afilm 40 μm in thickness.

COMPARATIVE EXAMPLES 1 TO 3

A thermoplastic norbornene resin, a PMMA, a PC and an EVA were mixed ineach predetermined amount according to the formulation shown in Table 1and kneaded in a predetermined condition by a plastomill (LABOPLASTOMILL MODEL 100C100, manufactured by Toyo Seiki Kogyo, Ltd.) toobtain a polymer blend.

The obtained polymer blend was heat-pressed at 185° C. to manufacture afilm 40 μm in thickness.

With regard to the polymer alloys obtained in Examples 1 to 6 and thepolymer blends obtained in Comparative Examples 1 to 3, the phasetransition temperature and the size of the phase separation structurewere evaluated according to the following methods. Also, with regard tothe films manufactured in Examples 1 to 6 and in Comparative Examples 1to 3, the total light transmittance was evaluated according to thefollowing method.

The results are shown in Table 1.

[Phase Transition Temperature]

The glass transition temperature when the temperature was finally raisedin a temperature condition program carried in the order of the following(1) to (6) by using DSC2920 Modulated DSC manufactured by TA Instrumentswas defined as the glass transition temperature used in the presentinvention.

(1) The temperature is dropped at a rate of 10° C./min from ambienttemperature to −50° C. and maintained at −50° C. for 5 minutes.

(2) The temperature is raised at a rate of 10° C./min from −50° C. to280° C. and maintained at 280° C. for 5 minutes.

(3) The temperature is dropped at a rate of 10° C./min from 280° C. to−50° C. and maintained at −50° C. for 5 minutes.

(4) The temperature is raised at a rate of 10° C./min from −50° C. to280° C. and maintained at 280° C. for 5 minutes.

The condition of the measurement of phase transition temperaturecorresponds to that of a heat cycle test for the polymer alloy to bemeasured. Accordingly, the case where a variation between the phasetransition temperature measured without running any heat cycle and thephase transition temperature measured when the heat cycle was repeatedthree times under the above-mentioned measuring condition of phasetransition temperature was 0.5α or less was defined as ∘ and the casewhere the above-mentioned variation exceeded 0.5α was defined as X toevaluate each sample.

[Size of the Phase Separation Structure]

The phase separation structure was observed using a transmission typeelectron microscope and evaluated according to the following standard.

-   ∘: 100 nm or less.-   X: More than 100 nm.    [Total Light Transmittance]

A haze meter (HCIIIDPK, manufactured by Tokyo Denshoku Co., Ltd.) wasused to measure the total light transmittance according to JIS K 7150.

TABLE 1 Comparative Comparative Comparative Example 1 Example 2 Example3 Example 4 Example 5 Example 6 Example 1 Example 2 Example 3 Material(parts by weight) Solvent H₂O MeOH CO₂ H₂O H₂O H₂O None None None 38 38— 38 38 38 — — — Thermoplastic resin 4 4 4 4 4.5 4 40 40 40 norbornaneresin PMMA 1 1 1 — — — 10 — — PC — — — 1 0.5 — — 10 EVA — — — — — 1 — —10 Condition Mixing temperature 400 300 200 400 400 400 230 230 230 (°C.) Mixing pressure (MPa) 30 35 35 30 30 30 0.1 0.1 0.1 Mixing time(minute) 5 5 180 5 5 5 15 15 15 Results of evaluation Glass transition149 150 161 155 158 96 108 141 78 temperature (° C.) Melting point (°C.) 161 161 161 161 Variation in phase ∘ ∘ ∘ ∘ ∘ x x x x transitiontemperature Size of phase ∘ ∘ x ∘ ∘ ∘ x x x separation structure Totallight 90 88 62 89 91 70 56 59 32 transmittance (%)As is clear from Table 1, the films of Examples 1, 2, 4 and 5 using thepolymer alloy containing a thermoplastic norbornene resin had hightransparency.

INDUSTRIAL APPLICABILITY

According to the present invention, a polymer alloy, a method forproducing the polymer alloy and a molded product and an optical filmwhich is obtainable by using a polymer alloy can be provided.

1. A method for producing a polymer alloy containing no air bubbles,which comprises at least: a step 1 of mixing two or more resinsincompatible with each other at ambient temperature and pressure with asolvent being in a liquid or gas state at ambient temperature andpressure; a step 2 of heating and applying pressure to said solvent intoa high-temperature and high-pressure fluid or a supercritical fluid andmixing the solvent in this state; and, a step 3 of cooling the mixtureobtained in said step 2 rapidly to the glass transition temperature orless without releasing the pressure of the mixture.
 2. A method forproducing a polymer alloy containing no air bubbles, which comprises atleast: a step 1 of mixing two or more resins incompatible with eachother at ambient temperature and pressure with a solvent being in aliquid or gas state at ambient temperature and pressure; a step 2 ofheating and applying pressure to said solvent into a high-temperatureand high-pressure fluid or a supercritical fluid and mixing the solventin this state; and, a step 3 of cooling the mixture obtained in saidstep 2 rapidly to ambient temperature or less without releasing thepressure of the mixture.
 3. The method for producing a polymer alloyaccording to claim 1, wherein the volume of the solvent in the mixtureof the two or more resins incompatible with each other at ambienttemperature and pressure and the solvent being in a liquid state atambient temperature and pressure is equal to or more than the totalvolume of said two or more resins incompatible with each other atambient temperature and pressure.
 4. The method for producing a polymeralloy according to claim 1, wherein the two or more resins incompatiblewith each other at ambient temperature and pressure are a thermoplasticnorbornene resin and one or more resins incompatible with thethermoplastic norbornene resin.
 5. A polymer alloy being obtained by themethod for producing a polymer alloy according to claim 1, wherein, atleast, when a phase transition phenomenon is observed by using adifferential calorimeter, the phase transition phenomenon of any resinamong said two or more resins disappears or the phase transitionphenomenon is observed at a temperature differing from the temperaturesoccurring the phase transition phenomenon of each resin.
 6. The polymeralloy according to claim 5, wherein when the highest and lowesttemperatures among the glass transition temperatures of two or moreresins incompatible with each other at ambient temperature and pressureare Tg_(H) and Tg_(L), respectively, and an absolute difference betweenTg_(H) and Tg_(L) is α, a glass transition temperature Tg of the polymeralloy is in the range of Tg′ ±0.1 α for Tg′ calculated by the followingequation (1):Σ(w_(i)/Tg_(i))=1/Tg′  (1) in the formula, w_(i) represents the weightpercentage of a resin i and Tg_(i) represents the glass transitiontemperature of a resin i.
 7. The polymer alloy according to claim 5,wherein when the highest and lowest temperatures among the glasstransition temperatures of two or more resins incompatible with eachother at ambient temperature and pressure are Tg_(H) and Tg_(L),respectively, and an absolute difference between Tg_(H) and Tg_(L) is α,a variation in the glass transition temperature of the polymer alloy iswithin 0.3 in the case of processing the polymer alloy in a heat cycleincluding the requirement for the condition heated to at least its glasstransition temperature or more.
 8. The polymer alloy according to claim5, wherein said polymer alloy comprises a transparent resin and at leastone or more resins incompatible with the transparent resin and, saidtransparent resin and the resins incompatible with the transparent resinform a ultra-micro-phase separation structure 100 nm or less in size. 9.A molded article, which is obtained by molding the polymer alloyaccording to claim
 5. 10. A transparent molded article, which isobtained by melt-molding the polymer alloy according to claim
 5. 11. Amethod for producing a molded article according to claim 9, whichcomprises molding at a temperature higher than the phase transitioninitiation temperature of the polymer alloy ultra-micro-phase separationstructure found by a differential calorimeter.
 12. An optical film,which is obtained by using the polymer alloy according to claim
 5. 13.The method for producing a polymer alloy according to claim 2, whereinthe volume of the solvent in the mixture of the two or more resinsincompatible with each other at ambient temperature and pressure and thesolvent being in a liquid state at ambient temperature and pressure isequal to or more than the total volume of said two or more resinsincompatible with each other at ambient temperature and pressure. 14.The method for producing a polymer alloy according to claim 2, whereinthe two or more resins incompatible with each other at ambienttemperature and pressure are a thermoplastic norbornene resin and one ormore resins incompatible with the thermoplastic norbornene resin. 15.The method for producing a polymer alloy according to claim 3, whereinthe two or more resins incompatible with each other at ambienttemperature and pressure are a thermoplastic norbornene resin and one ormore resins incompatible with the thermoplastic norbornene resin. 16.The polymer alloy according to claim 6, wherein when the highest andlowest temperatures among the glass transition temperatures of two ormore resins incompatible with each other at ambient temperature andpressure are Tg_(H) and Tg_(L), respectively, and an absolute differencebetween Tg_(H) and Tg_(L) is α, a variation in the glass transitiontemperature of the polymer alloy is within 0.3 in the case of processingthe polymer alloy in a heat cycle including the requirement for thecondition heated to at least its glass transition temperature or more.17. The polymer alloy according to claim 6, wherein said polymer alloycomprises a transparent resin and at least one or more resinsincompatible with the transparent resin and, said transparent resin andthe resins incompatible with the transparent resin form aultra-micro-phase separation structure 100 nm or less in size.
 18. Thepolymer alloy according to claim 7, wherein said polymer alloy comprisesa transparent resin and at least one or more resins incompatible withthe transparent resin and, said transparent resin and the resinsincompatible with the transparent resin form a ultra-micro-phaseseparation structure 100 nm or less in size.
 19. A molded article, whichis obtained by molding the polymer alloy according to claim
 6. 20. Amethod for producing a molded article according to claim 10, whichcomprises molding at a temperature higher than the phase transitioninitiation temperature of the polymer alloy ultra-micro-phase separationstructure found by a differential calorimeter.